Research Groups

Plasma Astrophysics Group

The group’s main effort has been
focused on developing detailed physical models of astrophysical environments
where both rotation and ordered and/or chaotic magnetic field are important.
These include the origin of astrophysical jets from magnetized accretion disks,
the accretion of plasma to rotating magnetized stars. These problems are
unavoidably complicated in that they involve calculations of multi-dimensional
magnetohydrodynamic flows.

Estimates of the filling
fraction for ionized particles in the interstellar and intergalactic medium
range from a few percent to 100 percent. As shown by Earth's ionosphere where
the ionization fraction can be less than one percent, plasma processes can be
important even for very low filling fraction. Plasmas are a combination of
neutrals, ions, electrons and fields that have conductive and collective
effects and where interparticle dynamics is not dominated simply by binary
collisions. This condition applies for most astrophysical systems. Even though
space plasmas usually maintain quasi-neutrality to within less than about 1
part per million, there can still be substantial currents, convection, plasma
flows, plasma waves and shocks and other plasma effects that interconnect
plasmas over vast expanse as demonstrated by direct measurements of solar
system space plasmas. Radio jets, interstellar shocks, stellar systems
(especially neutron stars), and many astrophysical phenomena now appear to
involve important plasma effects. Plasma astrophysics is the cutting edge of
21st century astrophysics and cosmology studies.